The Massachusetts Supreme Judicial Court last week ruled that law enforcement within the state can no longer surveil the metadata of a mobile phone or track a mobile phone without first obtaining court approval.

Citing 2012’s U.S. Supreme Court ruling on United States v. Jones as precedence, the Massachusetts Supreme Judicial Court used Associate Justice Samuel Alito’s concurrence as a primary argument.

“[R]elatively short-term monitoring of a person’s movements on public streets accords with expectations of privacy that our society has recognized as reasonable,” the justice argued. “But the use of longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy. For such offenses, society’s expectation has been that law enforcement agents and others would not — and indeed, in the main, simply could not — secretly monitor and catalogue every single movement of an individual’s car for a very long period.”

The case of Commonwealth of Massachusetts v. Augustine centered around the Massachusetts State Police gathering two weeks of the plaintiff’s mobile phone records from Sprint via federal legislation (18 U.S. Code § 2703) and not direct approval from the state courts. The plaintiff, Shabazz Augustine, was a suspect in the murder of Julaine Jules.

Investigators obtained the data as part of a criminal investigation in order to trace where Augustine was prior to the murder. Ultimately, the state would indict Augustine for murder, based partly on the mobile phone data obtained by police. The state appealed a lower court’s decision that ruled that the state police’s actions violated the state constitution.

“Even though restricted to telephone calls sent and received (answered or unanswered), the tracking of the defendant’s movements in the urban Boston area for two weeks was more than sufficient to intrude upon the defendant’s expectation of privacy,” read the 5 – 2 majority opinion.

This ruling adds to an increasingly contradictory set of precedence on cell phone tracking. On July 18, 2013, in the case of State of New Jersey v. Earls, the New Jersey Supreme Court ruled, “Using a cell phone to determine the location of its owner … is akin to using a tracking device and … involves a degree of intrusion that a reasonable person would not anticipate.”

Shortly after the New Jersey ruling, the United States Fifth Circuit’s Court of Appeals ruled 2 – 1 that probable-cause warrants are not needed to access cell phone location information. The court ruled that cell phone records are business records that were never in the subscriber’s possession and, therefore, are not protected under the Fourth Amendment’s protection against illegal search and seizures.